Cellular network consists of multiple base stations, each of which has a coverage area. Mobile devices, such as cellular phones, smart phones, tablets, and portable computers, wirelessly connect to these base stations to receive services such as data and voice connectivity. Base stations are connected together and to other networks through the core network. Previously, core network standards supported circuit-switched connections for voice calls. However, in recent years, service providers added packet-switched features to the core network as these packet-based features became more popular in the wireless interface between the mobile device and the base station. These packet-switched features allow networks to support voice communications through Voice over Internet Protocol (“VoIP”) (e.g., through an application running on a portable computer). However, these new features are not supported by every service provider. As a result, standards organizations have added messaging to allow cellular networks to advertise their features to mobile devices that are connected to the cellular network. These new features, and the associated information sharing, have added additional complexity to the interactions between mobile devices and the cellular network.